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Discussion Starter #1
Hi all...

I just rebuilt the carb on an 8hp tecumseh from an MTD snowblower and can't quite get it dialed in right.

The work done included:

- fuel and primer lines
- idle mixture screw and o-ring
- main jet, mixture screw, o-ring, and washer
- fuel inlet needle and seat
- check and clean all passages
- new carb to inlet gasket

Everything went well in the process, the float was set to 11/64, the idle mixture 1 turn out, and the main jet to 1.5 turns.

The engine starts easy and runs however I cannot seem to get rid of a small "pop" or "miss" at high speed. It isn't a consistent thing and seems to "come and go." I've re-checked everything over and over again and can't seem to find the cause. I can get the engine to level out and run fine, shut it down and 5 minutes later start it up to find the "pop" has returned and stays! It's driving me CRAZY! LOL

I'm not overly familiar with tecumseh products, is there anything I'm missing or anything know to cause this issue?

Thanks for your help!
 

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Almost every older tecumseh I have had in my shop will "pop" once in a while at high speed, I always attributed to lean running and loose valve clearances on exhaust. Check for cylinder gasket leakage with leakdown test and it will also tell you if your exhaust valve needs attention. Hope I helped a little.:fing32:
 

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Keep in mind you're not dealing with a Honda here, or even a Briggs for that matter. If you can get it to idle OK, and it accelerates without hesitation, that's about as good as it's going to get. I've seen brand new Tecumseh snowblower engines run just as you describe right out of the box. The average customer won't even think about is while it's keeping him or her from shoveling a foot of snow.
 

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This is typical of a lean carb ...meaning the idle passage might be restricted....Tecumseh carbs can be difficult to rebuild ....if it is really driving you "insane" buy a new carb .....you may find come winter time you'll need a richer mixture ,to drive the snowblower and throw snow ...if the carb is running lean ,look for a bright red hot muffler ,and the engine may die under an extreme load ,for lack of fuel.....

You can always run some seafoam thru the carb ,and see if this helps ....

My 2 cents,Jim
 

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Discussion Starter #5
Thanks for the replies!

I have it idling perfectly and it throttles up smoothly. I removed the carb and checked everything one more time. I verified all the passages were open re-set everything again. It still has the pop but not as often. I'll give it a leak down and see how that goes.

This machine has been used quite heavily and it came to me because it wouldn't run unless choked. You could tell from the start it was a lean problem. It's almost at the end of it's service life anyhow. The shave plate was ground down beyond the housing, the tracks and drive wheels are at the end of their adjustment, and the blower cage was bent to the point it needed strengthening. I think it's time to discuss retirement to some place hot and steamy like a melt down furnace!

I think I have it as good as it's going to get!
 
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